Are you referring to the Titles in the sidebar? If so you can add this to your CSS –

.sidebar .widgettitle {
color: red;
}

If you want to change the link colors in the sidebar, then you could add this –

.sidebar a {
color: blue;
}

I just used red and blue as examples. You can use a hex code if you want since that’s the preferred way. If you have a color you want to use and need help finding the code for it, just let me know and I can add it in.